Archive for the 'Symbian' Category

Finally, after months of developments (read: delays!), version 1.1 is ready for your download. This release contains major feature enhancements, namely support for Nokia native codecs (we use code name APS-Direct for this feature) and a new Audio Device API.

APS-Direct is our codename for functionalities to use the hardware codecs that are supported by sound devices e.g. Nokia Audio Proxy Server (APS) and/or VoIP Audio Services (VAS) directly, bypassing media processing in PJMEDIA. The Nokia APS and VAS support codecs such as G.711 (PCMA and PCMU), G.729, iLBC, and AMR-NB, though the availability of these codecs may vary according to the handset types. There are significant benefits of using these codecs instead of software codecs (in PJMEDIA-CODEC), with the main benefits are performance (hardware vs software codecs, latency) and the given codec licenses/royalties. Due to these benefits, the ability to use these codecs in PJSIP applications is very desirable, hence the support.

This has been a major development in PJMEDIA, as traditionally PJMEDIA works with PCM (linear, L16) audio samples. With APS-Direct, audio frames from the sound device are in encoded format, so some components along the media path need to be updated to support encoded frame format. Understandably, some features cannot be used when encoded audio is active, for example the mixing feature of the conference bridge. Please see APS-Direct wiki for more information.

Half way during APS-Direct development, we discovered that the existing sound device abstraction API couldn’t cope with the new features, for example handling of encoded frames, setting the audio device routing, etc. We could of course patch it here and there, but we decided that creating a new one would be a much better alternative. So a new Audio Device API was developed.

For more information about this release, start from the PJSIP Download page. Enjoy!

As we finish the current iteration of Symbian S60 implementation, mostimportantly the implementation of APS-direct, we need all of you toparticipate in testing it. This is from experience we know mobiledevices are very tricky and can behave differently from one firmwareto another.

So we need as many Symbian S60 3rd Edition phone as possible. The test will involve installing a test application, checking a few things, and filling in a report form

To do this we need your IMEI and a few other details, this is becausethe requirements of Symbian Signed, we need to ‘burn’ your IMEI intoour test application.

In the first two hours of the I’ve been listening to Symbian itself, but also Motorola, Sony Ericcson, and Nokia.

I’ve lost count of how many times ‘open source’ is mentioned. Nigel Clifford, Symbian’s CEO, mentioned a figure of $300m in royalty revenues to be ‘given back’ to the ecosystem.

That’s a really clever way of putting it. He did admit some of them will be ‘pocketed’ instead of being used to ‘innovate’.

Which is another rather overused word during the whole show. One of the main argument for going open source is innovation over control.

Of course, one can always say Apple seemed to be able to out-innovate everyone in the mobile space, by having total and absolute control (Benoit Schillings, Qt CTO, alluded to a ‘dictator’ style of development).

So the strategy to beat Apple (and to a lesser extent Microsoft and Linux) is to club together in the Symbian Foundation, and using open source as the common denominator, a level playing field.

Number of devices already shipped, number of companies involved is frequently cited. It is hoped the ‘ecosystem’ will be large enough to eclipse (pun intended) other mobile platforms. The newly appointed Executive Director Lee Williams, also do not want to put a ‘30% tax’ on the ecosystem.

It worked in the software tools space with Eclipse, but a mobile platform is a different beast altogether.

You can read up other thoughts on this matter from Dean Bubley and Simon Judge. Incidentally I can answer Simon’s wondering about UIQ: It’s officially dead. Patrik Olsson, VP and Head of Software at Sony Ericsson, said ‘you can get ready for Symbian Foundation-based Sony Ericsson phones now by using S60’.

This is an interim release, intended to mark the end of features development in the trunk. From now on, it will be tests and bug fixes only, until we reach 1.0. This will be our first proper stable release, and it will be given a separate branch, to isolate it from bleeding edge developments in the trunk.

Because of that, there has been a bit of “pressure” to stuff in as much features as possible on this release, since this is the last change to include them in 1.0. Here are some of them:

Integration of Intel® IPP Codecs. This brings us with bunch of new codecs into PJMEDIA, such as G.722.1, G.723.1, G.726, G.728, G.729A, AMR NB, and AMR WB. Basically the lot! For more info about this integration, please see here.

New Python API. We discussed this on this blog a month ago here, basically it’s a new Python API for PJSUA-LIB, it’s much easier to use, and it also has a more thorough documentation/tutorial. Please check that out.

Nokia APS Support. The Nokia Audio Proxy Server is a wrapper to Nokia S60 sound device, it has much lower latency than Symbian MMF API (the traditional sound device that we support), and it also opens up support for device’s native codecs such as AMR, G.729, and iLBC which we can use in the future. Although this API has been deprecated by Nokia in FP2, still there are lots of S60 and FP1 devices out there, so this is worth supporting.

New Echo Suppressor. Good for mobile devices, we discussed this in this blog here.

And some more. For more information regarding this release, please visit the download page.

As many have probably experienced it first hand, the echo suppressor (ES) in pjmedia sucks, to put it mildly. And this has made matters worse since ES plays such a major role in PDA’s and/or mobile devices/smartphones, since echoes are heavily present on these devices and we can’t really put the Accoustic Echo Canceller (AEC) on these devices due to the high processing requirements of the AEC (see our results in Evaluating PJMEDIA Performance article).

So we scrapped the old echo suppressor and wrote another one from scratch. And I think this one works quite well.

First of all, it’s low-complexity so it doesn’t require high processing requirements. We tested on a PocketPC 2003 PDA with 312MHz StrongARM CPU, it only uses less than 0.5% (half percent) of CPU. So it’s very affordable for these devices.

And most importantly, I think it works! It suppresses echo significantly, it lets non-echo audio pass through, and also it allows double-talk where both parties are talking at the same time. This is a very important to allow enjoyable conversation between two people, so we’ve made sure that the new echo suppressor supports this.

For those who care with the details, the ES works by comparing the audio level pattern in the input signal from the microphone with the audio level pattern in the playback signal during the learning process. It calculates the correlation values for each tail position up to the configured echo tail length, and finds out which tail position has the best correlation value. This position is then marked as the echo position. While doing this, the ES also notes the gain factors, that is how much de-amplification to be applied to the input signal in order to remove the echo from the input. Once the tail position is found, the ES then applies the appropriate gain factor according to the state of the conversation (e.g. I’m talking you’re silent, you’re silent I’m talking, we’re both talking, etc.).

This works pretty well. On the downside though, we noticed that the ES still seems to let a quiet echo to pass and transmitted back to remote party, depending on the signal level at the time. For now we allow this to happen since the echo level is very low and doesn’t seem to be too annoying, and lacking enough experience with the new algorithm we don’t want to make it cut signals too aggressively yet since it may inadvertently cut the “good” signal.

The new echo suppressor is available in SVN as pjmedia/echo_suppress.c, and it will be included in the next release.

Finally, after months of delay, PJSIP version 0.9.0 is released. This has been the longest gap (8 months) between releases, and consequently it has the most modifications in it (there have been 100+ tickets done on this release).

Some of the new features in this release:

many improvements in the audio, to reduce audio latency, to have better compatibility with more target platforms (Windows Vista issues have been fixed, as well as sporadic error reports for ALSA), and to maintain the audio quality against impairments such as clock drifts, bursty sound device, and of course, packet loss. Compared to version 0.8, I think we’ve improved audio latency by few hundred milliseconds.

support for TURN-07 in PJNATH, either as standalone client/server library, standalone client/server application (for testing purposes), or integrated with ICE-19. Just as we were the first to release open source ICE library, I think this is also the first open source TURN implementation out there. Unfortunately we haven’t had time to update it to TURN-08 as this draft was released late during our QA phase, but we’ll update it as soon as possible.